procutil: make stream detection in make_line_buffered more correct and strict
In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.
Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.
The new logic is different in two ways:
First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.
Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.
The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.
#require unix-permissions no-root reporevlogstore
$ cat > $TESTTMP/dumpjournal.py <<EOF
> import sys
> for entry in sys.stdin.read().split('\n'):
> if entry:
> print(entry.split('\x00')[0])
> EOF
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=">> $HGRCPATH
$ teststrip() {
> hg -q up -C $1
> echo % before update $1, strip $2
> hg parents
> chmod -$3 $4
> hg strip $2 2>&1 | sed 's/\(bundle\).*/\1/' | sed 's/Permission denied.*\.hg\/store\/\(.*\)/Permission denied \.hg\/store\/\1/'
> echo % after update $1, strip $2
> chmod +$3 $4
> hg verify
> echo % journal contents
> if [ -f .hg/store/journal ]; then
> cat .hg/store/journal | "$PYTHON" $TESTTMP/dumpjournal.py
> else
> echo "(no journal)"
> fi
> if ls .hg/store/journal >/dev/null 2>&1; then
> hg recover --verify
> fi
> ls .hg/strip-backup/* >/dev/null 2>&1 && hg unbundle -q .hg/strip-backup/*
> rm -rf .hg/strip-backup
> }
$ hg init test
$ cd test
$ echo a > a
$ hg -q ci -m "a" -A
$ echo b > b
$ hg -q ci -m "b" -A
$ echo b2 >> b
$ hg -q ci -m "b2" -A
$ echo c > c
$ hg -q ci -m "c" -A
$ teststrip 0 2 w .hg/store/data/b.i
% before update 0, strip 2
changeset: 0:cb9a9f314b8b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
saved backup bundle
transaction abort!
failed to truncate data/b.i
rollback failed - please run hg recover
(failure reason: [Errno *] Permission denied .hg/store/data/b.i') (glob)
strip failed, backup bundle
abort: Permission denied .hg/store/data/b.i'
% after update 0, strip 2
abandoned transaction found - run hg recover
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
b@?: rev 1 points to nonexistent changeset 2
(expected 1)
b@?: 736c29771fba not in manifests
warning: orphan data file 'data/c.i'
checked 2 changesets with 3 changes to 2 files
2 warnings encountered!
2 integrity errors encountered!
% journal contents
00changelog.i
00manifest.i
data/b.i
data/c.i
rolling back interrupted transaction
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 2 changesets with 2 changes to 2 files
$ teststrip 0 2 r .hg/store/data/b.i
% before update 0, strip 2
changeset: 0:cb9a9f314b8b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
abort: Permission denied .hg/store/data/b.i'
% after update 0, strip 2
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 4 changesets with 4 changes to 3 files
% journal contents
(no journal)
$ teststrip 0 2 w .hg/store/00manifest.i
% before update 0, strip 2
changeset: 0:cb9a9f314b8b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
saved backup bundle
transaction abort!
failed to truncate 00manifest.i
rollback failed - please run hg recover
(failure reason: [Errno *] Permission denied .hg/store/00manifest.i') (glob)
strip failed, backup bundle
abort: Permission denied .hg/store/00manifest.i'
% after update 0, strip 2
abandoned transaction found - run hg recover
checking changesets
checking manifests
manifest@?: rev 2 points to nonexistent changeset 2
manifest@?: 3362547cdf64 not in changesets
manifest@?: rev 3 points to nonexistent changeset 3
manifest@?: 265a85892ecb not in changesets
crosschecking files in changesets and manifests
c@3: in manifest but not in changeset
checking files
b@?: rev 1 points to nonexistent changeset 2
(expected 1)
c@?: rev 0 points to nonexistent changeset 3
checked 2 changesets with 4 changes to 3 files
1 warnings encountered!
7 integrity errors encountered!
(first damaged changeset appears to be 3)
% journal contents
00changelog.i
00manifest.i
data/b.i
data/c.i
rolling back interrupted transaction
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
checked 2 changesets with 2 changes to 2 files
$ cd ..